In businesses using computers, a worker often uses a plurality of applications simultaneously. In such a case, it is important to keep associating data, such as documents and images, with each other used in each application (including business data) with the business. This is because association of each business and data related to the business, for example, facilitates the worker to resume the business after once stopping the business.
Further, the data associated with the business is possibly utilized such as for assessing businesses similar to said business, extracting a file (data) that is considered necessary to carry out said business from data associated with the similar businesses, and thereby informing the worker of the file.
Patent Literatures 2, 4, and 5 disclose techniques for associating data with each other. Patent Literature 2 discloses a technique in which similarity of data is calculated based on keywords included in the data, and the data are associated with each other based on the similarity thereof. Patent Literature 4 discloses a technique in which data are associated with each other based on simultaneity of access time to the data. Patent Literature 5 discloses a technique in which copy and paste operations are detected on a computer, and data between the copy source and the copy destination are associated with each other.
Besides the techniques for associating data with each other, Patent Literatures 1, 3, 6, 7, and 8 disclose techniques that utilize line of sight information that denotes the line of sight of a user. The video playing device of Patent Literature 1 classifies a video or a video section to be played according to the degree of user's concentration on the video. Then, the video playing device selects a video or a video section to be played based on the classification result and the degree of user's concentration on the video. The liquid crystal display device of Patent Literature 3 computes the visual line angle of an audience with a television, and displays a video of image quality adjusted to the position of the audience. The work training system of Patent Literature 6 displays on a head-mounted display device the footage of a virtual vehicle and a virtual component that moves correspondingly to the movement of an operator.
Further, Patent Literature 7 discloses a technique of controlling a computer apparatus based on eye-tracking information. Patent Literature 8 discloses a technique of displaying feedback data on a display screen based on the absolute position of the gazing point of a user.